Home – Home – Jornals – Avtometriya 2010 number 6

The raw-material base of the Russian aluminum-producing industry is considered. The raw materials include common (boxites, nepheline syenites) and uncommon (synnyrites, anorthosites, power-and-heating plant ashes, kaolines) types of ores. With regard to many criteria (reserves and quality of ores, technology of their processing, etc.), the problem of alumina deficit can be solved by mining sillimanite group minerals Al₂SiO₅ (wt.%: Al₂O₃ = 62.9, SiO₂ = 37.1), namely, andalusite, sillimanite, and disthene. Their explored reserves converted to the final product (aluminum) exceed 400 mln tons. This will be enough for more than a hundred years on condition that aluminum will be produced in the present-day output (>4 mln tons in 2008). Almost all deposits can be explored by strip mining, with application of the gravity, flotation, and electromagnetic separation methods for aluminum concentration. The alumina content in concentrates reaches 60-62 wt.%. Only high-quality boxites and the above concentration methods can ensure such a high yield of Al₂O₃. Sillimanite group minerals can be processed together with nepheline ores by sintering or be used for the direct electrothermal production of silumin and aluminum, excluding the alumina production stage. The latter method is the most promising in Russia.

The validity of the Rb/Sr isotopic ages of Cretaceous granitoid complex in the central Chukchi region has been verified. The performed studies showed that the Rb/Sr isotopic ages of late-orogenic granitoids are not reliable. Their variation can be explained in terms of the mixing of primary mantle magmas with continental-crust matter. Most probably, the variation is due to the constant compositions of mixing components and their proportions.

Iron valence state and local environment in a set of fibrous diamonds from Brazilian and Congolese placers were investigated using X-ray absorption and Mossbauer spectroscopies. It is shown that the diamonds could be divided into two main groups differing in the type of dominant Fe-bearing inclusions. In the first group Fe is mostly trivalent and is present in octahedral coordination; diamonds from the second group contain a mixture of Fe²⁺ and Fe³⁺, most likely, with Fe²⁺ in dodecahedral coordination. A few other diamonds contain iron in a more reduced state: The presence of metallic Fe and Fe₃O₄ is inferred from XAS measurements. Spatially resolved XANES and Mossbauer measurements on polished diamond plates show that in some cases the Fe valence state may change considerably between the core and rim, whereas in other cases Fe speciation and valence remain constant. It is shown that Fe valence does not correlate with water and/or carbonate content or ratio, suggesting that iron is a minor element in the growth medium of fibrous diamonds and plays a passive role. This study suggests that, when present, evolution of the C isotopic composition with diamond growth is largely due to changes in chemistry of the growth medium and not due to variations of f _{O 2}

In light of the new clinoform structural model of the Neocomian, introduced at the last stratigraphic meeting, it is suggested to distinguish clinoform units instead of formations in the clinoform zone. Formations (12 in number) remain only west of the central part of the Neocomian basin (east-dipping clinoforms). In the eastern and southeastern zones of the basin, all the formations beyond the clinoform zone, which consist mostly of continental sediments, should be united into the Ust'-Taz Group.

The paper presents the results of a comprehensive investigation into the recent sediments of Proval Bay. This bay formed during catastrophic flooding of a big block of land as a result of an earthquake in 1862. Comparison of the sketch map of the bay for 1862 with its modern map shows that the boundary of the Selenga River delta has shifted considerably eastward. The sedimennts of Proval Bay are sands, silty pelite, and pelitic silt. Terrigenous material is predominant and consists of mineral grains and land plant remains admixed with diatom frustules and sponge spicules. In the southwestern part of the bay, turbidites and a soil layer have been found. The latter was buried when the water level in Lake Baikal rose after the construction of the Irkutsk dam in 1959-1964. In the northeastern part of the bay, a peatlike layer has been found in the bottom sediment core. It formed in Lake Beloe, which existed in the Tsagan steppe before the 1862 earthquake. According to diatom analysis, this lake was shallow and eutrophic. The sedimentation rates in different parts of Proval Bay differ greatly and depend directly on proximity to the Selenga River. Variations in the geochemical indicators which reflect the ratio of organic to clastic components in the bottom sediments of the bay are controlled by temperature and water level variations in Lake Baikal.

A new algorithm is suggested for the joint calculation of three key parameters of reservoir rocks: permeability, electroacoustic constant, and velocity of second bulk compressional wave (slow wave). The algorithm is advantageous in the use of Stoneley waves which are most stable in acoustoelectric log waveform data.

This paper describes a well logging method and device designed to determine radial inhomogeneities in the elemental content of the borehole environment with high spatial resolution. The sounding factor that determines the spatial resolution is the time elapsed from the moment of neutron emission from the device to the moment the device records the gamma rays from neutron inelastic scattering (inelastic gamma rays, IGRs) in the formation. The time interval characterizes the distance to the point of origin of a gamma ray, and the energy of a gamma ray passing through the formation without interaction determines the chemical element involved in inelastic scattering.
Simulations have shown that at each time, the density of inelastic scattering is very well localized in space owing to the small number of fast-neutron scatterings: on average, one to two events. It is the compact localization of inelastic scattering events that provides high radial resolution (and, if necessary, high azimuth resolution) during fast-neutron sounding of formations and measurement of unsteady IGR fluxes. Recording of IGR distributions over time also provides increasing sounding depth because powerful IGR fluxes from nearby regions reach the detector at short times and do not overlap the weaker IGR fluxes from distant regions because the latter reach the detector later.
To evaluate the radial resolution of the method, we calculated the response of the sonde for typical models of a borehole environment which include a borehole, an iron casing, cement, an invaded zone, and an uninvaded rock. The boundaries of spatial inhomogeneities and the elemental content in the regions between these boundaries were determined from time dependences of unscattered spectral lines in IGR spectra for the elements Ca, Si, C, O, and Fe. The results of the numerical simulation indicate a high sensitivity of the measurements to the radial boundaries and an adequate spatial resolution: about 1 cm at a 0.1 ns time sampling of logs. The interfaces between the radial zones are clearly marked in the time distributions by steep fronts with a length of 0.1 ns (at a collimation angle of the source of about 30?) to 0.15-0.4 ns (at an angle of 90?).
A method of solution was formulated for the inverse problem consisting of determining the boundaries of the radial zones and the elemental content in these zones. The problem is solved using a qualitative model of the borehole environment, for example, a "borehole-casing-cement-invaded zone-uninvaded rock" model. The method is based on searching for approximating model curves to measured time distributions of unscattered IGR fluxes jointly for all components of the model. The search is conducted by spatial optimization of the sought parameters - the distances { r_S} from the neutron source to the boundaries of the zones and the concentrations { C } of specified chemical compounds in these zones. The initial approximations for the sought parameters { r_S} and { C } are calculated by linear inversion of logs, which proves to be very accurate because the contribution of singly scattered neutrons to the inelastic scattering density at small times (10 ns) is, on average, 50-90%.
Model curves are calculated by numerical simulation of the transport of neutrons and gamma rays. An appropriate calculation method is the Monte Carlo technique. Since the multiplicity of neutron scattering is low and, for gamma rays, only the unscattered component is of interest, the numerical simulation is a fast process.
The practical implementation of the method requires the use of advanced developments in the design of neutron generators, spectral gamma-ray detectors, and fast analyzers for recording subnanosecond processes. Use of associated-particle neutron generators, Ge semiconductor detectors with electron cooling or LaBr₃ (Ce) and BaF₂ based fast scintillator blocks of high energy resolution will allow the application of the proposed method to logging measurements.

The superdeep North Caspian, South Caspian, and Barents basins have their sedimentary fill much thicker and the Moho, correspondingly, much deeper than it is required for crustal subsidence by lithospheric stretching. In the absence of large gravity anomalies, this crustal structure indicates the presence under the Moho of a thick layer of eclogite which is denser than mantle peridotite. Crustal subsidence in the basins can be explained by high-grade metamorphism of mafic lower crust. The basins produced by lithospheric stretching normally subside for the first ~100 myr of their history, while at least half of the subsidence in the three basins occurred after that period, which is another evidence against the stretching formation mechanism. According to the seismic reflection profiling data, stretching can be responsible for only a minor part of the subsidence in the Caspian and Barents basins. As for the South Caspian basin, there has been a large recent subsidence event in a setting of compression. Therefore, eclogitization appears to be a realistic mechanism of crustal subsidence in superdeep basins.

This is a critical comment on the model of basin formation by eclogitization of mafic crust suggested by E. Artyushkov. The eclogitization model bears uncertainties in average parameters (thickness, density, pressure) of lithospheric mantle, crust, and sediments, which may bias the estimates of subsidence magnitude. Main pitfalls, however, lie in high-pressure petrology: The lithostatic pressure is insufficient for eclogite to form in the lower crust beneath deep basins. It is shown that linear extrapolation of laboratory data on the gabbro-to-eclogite transition onto the field of relatively low pressures and temperatures in the lithosphere is incorrect. The hypothesized role of hot mantle fluids in the gabbro-eclogite transformation appears doubtful in terms of both petrology and kinetics of metamorphic reactions. Eclogite volumes in none of well known eclogitic sites agree with those required for eclogitization-driven subsidence. Artyushkov's criticism of the extension basin formation model is not quite just. There are recent models of a two-layer lithosphere that imply a possibility of brittle and ductile deformation at different crust rheologies. The models we refer to predict most of extension to occur in mantle lithosphere rather than in the crust, this extension being able to produce deep continental basins.

As a result of solution of the optimization problem, a new method for estimating the amplitude-phase distribution in multielement antenna arrays is proposed and studied by numerical simulation. The method is based on calculating the principal eigenvector of the spatial correlation matrix and increases the efficiency of classical and super-resolution methods for the spatial localization of a priori unknown broadband signals.

A problem of searching for man-made objects on the basis of remote sensing of the Earth is considered. It is proposed to perform this search at the pixel level by combined processing of initial images without their preliminary segmentation; each pixel should be characterized by both spectral and spatial (with allowance for the local neighborhood) features. The efficiency of the proposed searching method is quantitatively estimated by means of processing real images.

Relations for sampling functions in nonuniform sampling of a trigonometric polynomial and its derivatives are obtained.

A method for output-uniform coding of memoryless sources with unknown message statistics is proposed. The efficiency of this method is estimated. It is found that this coding is more efficient than coding uniform in input.

The paper considers an algorithm for nonlinear quasioptimal digital processing of signals with various types of angle modulation based on a generalization of the Capon minimum variance approach. The algorithm makes it unnecessary to compensate for the unknown frequency shift in the problem of determining the relative time delay of signals during multichannel propagation. Efficiency of the proposed method is demonstrated on phase- and frequency-shifted keyed signals which represent short information sequences.

The possibility of using nonparametric
algorithms of pattern recognition for
testing hypotheses on distributions of
random variables is discussed. Results
of computational experiments are
compared with the Kolmogorov-Smirnov
criterion.

The paper describes parallel transformations of the Walsh and Haar transforms with a time complexity O(log₂N), as well as the fast wavelet and saw-tooth transforms. The parallel calculation of the basis of the discrete Fourier transform is performed with a time complexity O(1); the parallel algorithm of the fast wavelet transform is estimated as having a time complexity O(log₂log₂N × log₂N).

Based on the well-known algorithm of the most likely estimates of the center frequencies of a normal narrow-band random process with a fractional rational spectrum, a similar algorithm for a process with a Gaussian spectrum is proposed and investigated by computer simulation. The practical importance of the development of algorithms for efficiently estimating the parameters of such processes is that they are a sufficiently close model of the output signal of laser Doppler systems used to study hydrodynamic and aerodynamic flows, measure the velocity of diffusely reflecting solid objects, and perform laser sensing of the atmosphere. The results of the studies show that the proposed algorithm does not shift estimates of the Doppler frequency (velocity), gives fairly accurate estimates (for a Doppler system with 25 interference fringes in the measuring volume at a measurement time equal to 100 Doppler periods, the error is only 0.12%), has high noise immunity, and evaluates the resulting errors.

This paper considers a method of using a posteriori information to correct control actions on a poorly formalizable dynamic object and a new design of an observer of unmeasurable variables based on the method of analytical design of aggregated regulators and the concept of recognition of the states of a complex object from the time series accompanying its operation. Numerical simulation results are given.

Operation regimes of an electrical energy microgenerator based on a multilayered structure consisting of a metal, a dielectric with a built-in charge, a microgap, and a moving electrode, whose operation principle is based on electrode vibrations in the force field of the space charge of the dielectric, are analyzed. Specific features of electromechanical conversion of energy due to vibrations of the electrode surface in submicron gaps are found. It is demonstrated that such microgenerators in the low-frequency regime (10-100 Hz) can produce power sufficient for providing energy for modern microcircuits (up to 1-10 mW/cm²) without using any other power sources.

This paper substantiates laser scribing conditions for fabricating mosaic photodetectors based on molecular beam epitaxial (MBE) p-type HgCdTe films on GaAs substrates without loss of image information at a spacing of photosensitive elements (10 µm in diameter) of not less than 46 µm. A scribing technique for linear array photosensitive elements of dimension 4×288 p-n junctions spaced at 56 µm intervals is described in which a two-level depth groove is formed in several passes. In the region of p-n junctions, the groove is formed by radiation with an average power of 1.4 mW, and outside this region, it is formed by radiation with an average power of 2 mW. The groove has varying depth: outside the p-n junction region, the grove is 120 µm deep and 22 µm wide, and in the junction region, it is 26 µm deep and 18 µm wide. It is shown that the laser radiation effect does not lead to accelerated degradation of the electrical parameters of the p-n junctions

The dependence of the thickness of the fluid film flowing down the sphere surface in the gravity field on the fluid flow rate and the polar coordinate is measured by an optical method. Comparisons of experimental data with theoretical estimates are demonstrated.

A new quasi-three-dimensional model of the laser welding of thin metal plates and a numerical algorithm of its implementation are proposed. Computations of thermophysical processes at a laser joining of titanium plates are carried out. It is shown that the new model adequately describes thermophysical and hydrodynamic processes occurring in the welding region.

Combustion of a pulverized coal torch has been numerically simulated on the basis of the equations of multicomponent turbulent two-phase flows. The results of three-dimensional simulation of conventional and plasma activated coal combustion in a furnace are presented. Computer code Cinar ICE was verified at coal combustion in the experimental furnace with thermal power of 3 MW that was equipped with plasma-fuel system. Operation of the furnace has been studied at the conventional combustion mode and with plasma activation of coal combustion. Influence of plasma activation of combustion on thermotechnical characteristics of the torch and decrease of carbon loss and nitrogen oxides concentration at the furnace outlet has been revealed.

On June 26, 2010  Vladimir V. Nakoryakov  the prominent Russian scientist working in the area of thermophysics, the Full Member of the Russian Academy of Sciences  became 75 years of age.

On June 17, 2010  Robert I. Nigmatulin  the prominent scientist specialized in mechanics and mathematics, the Full Member of the Russian Academy of Sciences  became seventy years of age.

On May 30, 2010  the Corresponding Member of the Russian Academy of Sciences, the Director of the Institute of Thermophysics SB RAS  Sergey V. Alekseenko  was 60 years of age.

On June 26, 2008  Professor Anatoly P. Burdukov  the Laureate of the State Prize in Science and Engineering, the Honored Worker of Russian Science  was 75 years of age.

Different classes of compounds exhibiting the properties of inhibitors for NO synthases are considered in the review. Literature data on natural and synthetic agents published between the years 2003 and 2009 are analyzed and systematized.

We consider the absorption and catalytic conversion of a single-stage method of obtaining high yield of pure hydrogen. This process involves simultaneous catalytic conversion of hydrocarbons into hydrogen and sorption removal of by-product - carbon dioxide. Different aspects of absorption and catalytic conversion are analyzed, including its technical implementation in flow reactors with fluidized and fixed bed, as well as high-temperature CO₂ absorbents and catalysts necessary for the process. It is shown that the preferred scheme for production of hydrogen from methane is that with two or more fixed bed reactors, loaded with a mixture of a conventional nickel containing catalysts of steam conversion and a high temperature reversible absorbent. The analysis of the perspective high-regenerated absorbent of CO₂: individual and deposited oxides of alkaline-earth metals, mixed lithium salts, promoted hydrotalcite. It is shown that the absorbents based on CaO have sufficient stationary dynamic capacity, stable under conditions of absorption and catalytic conversion, and optimal thermodynamic properties.

A technique was developed to remove and immobilize the cadmium ions from simulated industrial effluents. The cadmium ions were removed from industrial effluents by applying most economical method of sorption under certain physicochemical conditions. Removal of cadmium ions from industrial effluents using silica sand (originated from Ravi River) was studied to optimize the physicochemical conditions for maximum removal. The range of pH and temperature was optimized to get maximum removal of metal ions. Maximum removal (94-98 %) of cadmium was achieved with pH 10 and at temperature 25 ^oC. Under optimized conditions with temperature range of 298-318 K, ΔH, ΔS and ΔG₂₉₈ for 200 mg/L solution were -71.10±3.8 kJ/mol, -220.2±11.5 J/(mol · K) and -6.70±0.4 kJ/mol, respectively, and for 250 mg/L solution thermodynamic entities were ΔH = -108.7±5.7 kJ/mol, ΔS = -335.7±17.5 J/(mol · K) and ΔG₂₉₈ = -9.64±0.4 kJ/mol. This removal required certain physicochemical conditions; therefore, there were chances of desorption of the adsorbed metal ions under changed physicochemical conditions in final disposal. It was necessary to stabilize/immobilize sorbed metals ions by converting this "secondary waste" in a stable vitreous material having high resistance to leachibility. Such stabilization/immobilization of sorbed metal ions was obtained by converting the silica sand along with the sorbed cadmium ions into the glass matrix to prevent leaching/mobilization in final disposal under natural conditions. Stability of sorbed metals ions in final matrix was tested by desorption attempts in acidic and basic media and in ground water as well.

Data on the determination of petroleum products in surface and near-bottom water of Lake Baikal and its tributaries by means of express method (fluorometry, 168 samples) on board the research vessel are presented, as well as the data on n-alkanes and polycyclic aromatic hydrocarbons (PAH) obtained under laboratory conditions by means of gas chromatography/mass spectrometry. It was established that the oil product content of surface waters at the deep-sea stations of reference section does not exceed 10 μg/dm³, in water depth and in the near-bottom layer 5-7 μg/dm³, including n-alkanes - 0.15 μg/dm³, PAH (priority pollutants) - 0.012 μg/dm³; the concentration of benzo[a]pyrene is up to 10 times below MPC for drinking water (0.005 μg/dm³), total content of six PAH compounds under control in drinking water of EEC is up to 50 times lower than MPC_EEC (0.2 μg/dm³). Increased background of oil products reaching 50 μg/dm³ (MPC for fishery) was detected at limited regions of intense navigable waterways. Extremal concentrations of oil products (up to 1.3 · 10⁴ μg/dm³), n-alkanes (up to 500 μg/dm³), PAH (up to 20 μg/dm³) were discovered in the samples taken from the water surface of the lake in the regions of natural oil shows. With an increase in the distance from oil show boundaries (oil spots on water surface) the concentrations of oil products decrease sharply but exceed the average value for the water area of the lake almost by a factor of two (11 μg/dm³).

Comparative investigation of obtaining conditions and the "stability" of water-soluble intermolecular complexes of low-soluble pharmaceutical substances and different polysaccharides with β-cyclodextrin was carried out. Substantial improvement of the pharmacological characteristics of resulting complexes in comparison with initial pharmaceutical substances was demonstrated.

Fractional extraction of the sum of lichens of Cladonia genus was carried out. The effect of presowing treatment of the spring wheat seeds with the preparation obtained from the ethanol extraction of lichens on the development of root rot agents was considered. Rather high efficiency in suppression of root rod was confirmed. The stimulating effect of the preparation on growth processes and increase in wheat productivity was revealed.

The process of dissolution of asphalt-tar-paraffin deposits of paraffinaceous type in the gas condensate of alkane basis and a mixture of hexane with benzene at a temperature of 10 and 25 °С was investigated. The kinetic description of the process was made with the help of Erofeev-Kolmogorov equation. Kinetic parameters were calculated: rate constants, activation energies and orders of the reactions of dissolution of asphalt-tar-paraffin deposits in the solvents under investigation.

Single-phase membrane materials having the composition SrCo_{0.8 - x}Nb_xFe_0.2O_{3 - z} were obtained. The effect of doping with niobium on thermal stability and transport characteristics of the obtained compounds was studied. It was shown that the isomorphous substitution of cobalt ions with highly charged Nb⁵⁺ cations causes an increase in thermal stability of the compounds under investigation in the reductive atmosphere and suppression of the phase transition perovskite - brownmillerite, which is accompanied by acceptable decrease in oxygen permeability.

A process was studied concerning the combustion of municipal wastewater sediments from sludge fields of the Gorvodocanal Co. (Novosibirsk), in the fluidized bed of a catalyst. It was found that at the process temperature of 700 °C, the burnout level of the sediment amounted up to 98 %. In this case, the content of toxic substances (Hg, HCl, SO₃, P₂O₅, СО, NO_x meets the sanitary standards. It was demonstrated that the combustion of sediments is possible after its preliminary drying up to obtaining the moisture level equal to 54 %.

Potentialities were studied concerning the obtaining of hydrated antimony pentoxide (HAP) via much simpler methods than the method of SbCl₅ hydrolysis described in the literature. A sorption capacity was tested for the HAP obtained with respect to Cs⁺and Sr²⁺, whose, radionuclides are of environmental hazard when released into water basins. The oxides obtained were studied by means of powder X-ray diffraction method. It is established that the treatment of Sb powder by 16 M HNO₃ solution and the subsequent drying at 150 °C results in obtaining antimony tetroxide rather than pentoxide. Evaporation of antimony solution in nitrohydrochloric acid (aqua regia) and drying at the same temperature results in the formation of HAP, whose composition is close to Sb₂O₅ · 5H₂O. Adding HNO₃ to the solutions in the course of evaporation results in decreasing the hydration level. It was revealed that when HNO₃/HCl molar ratio in aqua regia is equal to 5 : 1 the HAP composition approaches to Sb₂O₅ · 3H₂O (H₃SbO₄), whereas with HNO₃/HCl = 9 : 1 therein the hydrate composition approaches to Sb₂O₅ · 2H₂O (H₄Sb₂O₇).

An effect was studied concerning the preliminary heating of activated carbon at the temperature of 250 °C on the porosity parameters of the adsorbent and the state of its surface. A comparative analysis was performed for the adsorption extraction of aniline and phenol from aqueous solutions by initial and pre-heated samples of the adsorbent. It was demonstrated that the thermal treatment of activated carbon causes an increase in the adsorption level of aniline and exerts almost no effect on the adsorption of phenol.

Results are presented concerning the optimization of composition and conditions for obtaining titanium-containing zeolite, a catalyst for allyl alcohol liquid-phase epoxidation by an aqueous solution of hydrogen peroxide in the methanol environment. The composition and conditions for catalyst preparation were revealed to provide a maximum yield of glycidol.

Five- and seven-membered cyclic ketals of 3-phenylsulphanylbutane-1,2,4-triol were obtained via thiolysis of 3,5,8-trioxaspiro[bicyclo[5.1.0]octane-4,1′-cyclohexane] thiophenol, followed by isomerisation. The syntheses were carried out using the methods of green chemistry (reactions in water without the use of organic solvents). The thiolysis in basic medium proceeds in a selective manner resulting in the formation of ketal from 1,3-dioxepane series only. In hot water, by the contrast, a mixture of isomeric spiroacetals is formed. The obtained β-hydroxysulphides and their acetates were oxidized to yield corresponding sulphones. The structure of the isomeric products was confirmed by the method of 1D and 2D NMR spectroscopy and
X-ray diffraction analysis.